Automatic telephone-switching system



Nove l, l 71 I K M. MATHlAS ATOMATIC TELEPHONE SWITCHING SYSTEM Filed Dec. 5, 1925 2 Sheets-Sheet 1 l" a S @El K H K* I l \l N G l \1 \l Q L l N Q n l iN Nov. l, 1927.

M. MATHIAS AUTOMATIC TELEPHONE SWITCHING SYSTEM Filed D60. 5, 1925 2 Sheets-Sheet 2 @Wwf/ET:

Patented Nov. l, 1927.

unirse srarss g tenete .career ortica.

MAXIMILIAN Marmite, or BERLIN, GERMANY, AssIeNon Y ro SIEMENS a IraLsnE aKrIENGEsELLscHAEn wEENEawEEK, or sIEMENss'ri-inr, NEAR BERLIN; enlaF MANY.

' AUTOMATIC TELE-ONE-S'WITCHNG SYSTEII.

Application filed December 5, 1925*, Serial No.` *S/l?, andn Germany January 22, 1925.

The present invention relates, broadly stated, to a ycircuit arrangement for automatic telephone systems with main and sub exchanges located in tandem, in which, when connections are set up over several sub-exchanges, the trunk lines `and connecting devices located beyond the wanted subscribers exchange are rendered available 'for other calls.

More particularly, the trunk line used for connectingthe main exchange with the nearest serially located sub-exchange is rendered available tor other calls when a train of ini- 'pulses transmittedfroin a calling substation has indicated that the connection is to be extended to one of the serially located sub exchanges.

The drawings 'show by way of example, one method of carrying out the invention, all those parts being omitted that are not reqllired for explaining the essence kol: the invention.

Figure 1 shows diagrammatically the arrangement ofthe connecting devices for a telephone system comprising a main exA change HA and two sub-exchanges, namely the sub-exchange UA and the intermediate exchange ZA. i Y

Figure 2 illustrates more detailed the method of setting up a connection.

' To a main exchange HA is connected an intermediate,exchange ZA and to the latter is connected a sub-exchange`A- The subscribers in the different exchanges are designated by Te 3200 and Te 3211 in the sub-exchange, by Te 3800 and Te 3311 in the intermediate exchange and by Te 44:11 in the main exchange. Calls originated in the sub-exchange UA and in the intermediate exchange ZA always pass over the switch LGVV in the main exchange. These calls may be local calls or calls from one subfexchange lo the other or to the main exchange. The switch LGVV is again released when the designation is given that either the intermediate exchange or the subexchange is wanted. For example a all trom the subscriber Te 3200` (see Figure 1) oi the sub-exchange UA to the subscriber Tc 3311 of the intermediate exchange A passes over the two preselectors I VVV and H VV, repeater Ue and its associated auxiliary register switch HS. trunkfline VL, repeater Ue 1 and its associated register switch lilSLinterinediate switch ZW, trunk line VL 1, trunk line VL 2 and GVV in the mainexehange HA. The switch LGV] in the main exchange as Well as the auxiliary register switches MS and MSl are positioned by the irst trainof impulses. According to the invention, in r4the in anner hereafter described, the trunk line V111 is interrupted'bythe operation of the register switch MS1, hence the second train` ot impulses can not reach the LGVV in the main exchange, but this train positions t-he register again, causing ythe intermediate switch ZW to seize `an idle trunk line VL 3 leading-to the desired exchange. Theother trains ot impulses required for reaching the wanted subscriber operate in known manner the final selector LV, which is reached over the trunk line VL 3. If the subscriber Te ltlwishes to make a local call, l'or example to the subscriber Te 3211, the second train` of nnpulses operates the register MS and the register causes the UVW to move onto another row oi contacts, whereupon the call to the wanted subscriber is set up over the trunk line connected to that row of contacts, for exan ple over VL i and the linal selector LVW. Similarly, when the subscriber Te 3300 of the intermediate exchangepmakes a local call to the subscriber Te 3311 or makes a call tothe subscriber Te 3211 of the sub-ex-` l change, after the connection has been switched over to another row of contacts at lLVlV in response to the setting of theauxiliary register switch MS2, the call is set up over the trunk line VL 5, ILGVV in the in` tcrmediate exchange and the final selector .UVV in the sub-exchange.

`The circuit arrangement according to the invention will now be described with refer- `ence to the Figure 2, which showsthe circuits more fully. By way of example it will be assumed that the subscriber Te 3200 of the subexchange UA wishes to setup a call to the subscriber Te 3311 of the intermediate exchange ZA'. Vhen he removes his regizes over the lead c. The circuit for the relay C 1 extends over: ground, battery, the two windings of T, wiper of IVW `and of IIVV, test lead c, winding I of the relay `C 1, off-normal contact 7c ground. In vorder to maintain itself energized after the ofi'- nornial contactc has been opened, the relay C 1 locks itself over its contact 1 c1. It also closes the following circuit over its Contact 2 01: ground, contact 2 c1, contact '3 a, winding of V 2 and of V 1, battery, ground. The relay A has opened its contact 3f a and has closed its contact 5 (L. Thereby the short circuit removed from the second winding of the relay C-1 and the relay V 2 is short circuited. The relay A has also opened its contact 4 a. Furthermore,'the relay C 1 has closed its contacts 6 c1 and 7 c1. Over the latter the following circuit is established: ground, front Contact T c1, test lead c', winding I of C Y2, off-normal contaet'8 is, battery, ground. The relay C2 is operated infthis circuit and locks itself over its contact 9 c 2 and its second winding. Furthermore, the relay C 2 at its Contact 10 c 2 closes a circuit for the rotary magnet D of the intermediate switch ZW as follows: ground, double front contact 10 c 2, back contact 11 p, rotary mag-net D, relay interrupter RU,vbattery, ground. The intermediate swith ZW rotates its wipers 12,. 18, 14, 15, until they encounter an idle line, for example VL 1, leading' to the main exchange HA. The test relay P belonging to this line is then energized in the following circuit: ground, double front contact 10 c 2, windings II and I of P, back contact 16 u 2, wiper 14, test vlead c, winding of C 3, battery, ground. The relay I), b y opening its contact 11 y?, disconnects the `rotary magnet D, and by closing its contact 17 p, it short circuits its second winding. Furthermore, by closing its contacts -60 p and 61p, the relay P switches througlrthe two talking conductors of VL. Over a branch of the just mentioned test circuit and iii-,parallel with relay C 3 an energizing circuit is also established for the relay S over the back contact 18 c 3. The relay S opens its contact 19 s and interrupts the test circuit for the subscriber Te 330() at the intermediate `to -the number of impulses transmitted.

These impulses, transmitted by the calling subscriber are repeated in a known manner 'from the bridging relay A 1 to the bridging relay of IGVY in the main exchange HA, whereby that switch is positioned. The transmitted impulses also operate the auxiliary register switch MS associated with the repeater Ue and cause it to more on. Although it is not shown in the drawing how the auxiliary switch MS is advanced by the impulses, it will be understood that the circuits may be similar to those shown in connection with switch MSI. In the repeater Ue, the contact 5 a of relay A was opened whenthe relay A was released and it caused the short circuit to be removed from the relay V 2. Hence the relay V 2 operates, and by closing its contact 23 yU 2 it establishes the following circuit for the relay B 1 of the repeater Ue 1: ground, battery, front contact 23 o 2, lower line conductor, back contact 24 f, winding of B 1, ground. The relay B 1 operates and, by opening its contact l25 "b1, it prevents the circuit of the relay F being prematurely established. After the Atransmission of the lirst train of impulses, t-he 'wiper 22 of MS 1 stands on the contact 27. Thereby the following circuit is completed: ground, back contact 26 a1, back contact 25 b1, wiper 22, contact 27, winding AI of the relay U 2, battery, ground. The relay `U 2 operates and by opening the contact 28 u 2 it removes the short circuit from its second winding. The relay U 2 by opening its contact 16 u 2 interrupts the test circuit of the line VL 1, and by closing its contact 29 u 2 it switches the test circuit over to the other test wiper 15 of the intermediate switch ZIV. T he relay Ii 2 also opens its contact 30 u 2 and so interrupts the upper line conductor of the trunk line exchange, so `he can not take the switch -VL LGIV at the main exchange into use during the setting up of the connection.

The calling subscriber now transmits the first train of impulses, namely the number 3, which is the rst digit of the wanted subseribers number. Thereby the impulse relay A at the repeater Ue is made to deenergize three times in rapid succession. This causes the contact 4 a to be closed three times to transmit three current impulses over The next train of impulses (the second digit 3 ofthe wanted subscriber-s number) only operate the two auxiliary switches MS located in the repeater Ue and MS 1 in the repeater Ue 1. The selector IGV at the main exchange can not be operated by the second train of impulses, because the impulse conductor is severed by the open contact 30 a 2. The transmitted train of impulses again vadvance the wiper 31 ot the auxiliary switch MS land the wiper 22 of the auxiliary switch MS 1 by three steps. Thereby nothing happens Iat the auxiliary switch MS, but at energized inthe following circuit: ground,

lthe wanted subscriber Te 3311.

back contact 26 al, back contact `25 1, wiper 22, contact 32, winding of F, battery, ground.' Relay F opens its contacts 20ff and 24 f. disconnecting the bridging `relays' A l and B l. F also switches through the upper line conductor of the trunk line VL by closing its contact 33 The relay U 2 as will be remembered locked itself over its second winding and keeps contact 30 u2 closed. By opening its contact 16 u 2, the circuit of relay P isy interrupted, whereupon relay P deenergizes, closing the contact 1l p and aga-in connecting the rotary magnet of thev intermediate switch ZV to the `relay interrupter RU. The switch ZW now ro tates its wipers until `they reach an idle line `in the second Contact row 63 (see Figure l),

to which the rlines 0oin0' Vto the intermediate exchange are'connected. Thereupon the tol lowing circuit 1s established: ground, double front contact 10 c 2, windings Il and I of P, front contact 29 u 2, wiper l5, test lead cl, winding of relay C 4, battery, ground. The wipers l2, 13, l5 now stand on the contacts 34, 35, 36. The calling subscriber now transmits the last two trains of impulses corresponding to the number l1. y bridging relays A. 2 and B 2 ot'k the tin-al Thereby the selector LNV areoperated in known manner and the switch is positioned on the line of The wanted subscriber is then signalled as usual. Then he answersy the call the setting upot the connection is completed. yVhen the subscribers restore their receivers, the connection is released in known manner and all the `devices used for setting up the call are returned to their normal position.'

,When the calling subscriber `Te 320() wishes to set up a call to a subscriber belonging to his own exchange UA,'1tor 'ex` ample the subscriber Te 3211, the following operations have to be considered: The first train ot impulses passes over the repeaters Ue and Ue l, the auxiliary switches MS and MS l to the first group selector at the main exchange HA in the manner described for the previous connection. After the first train of impulses, the line to' the main exchange is interrupted by the. energizing ot U 2. The second train ot' impulses (second digit 2 of the wanted number) advances the wipers 8l and 22 oit the auxiliary switches MS and MS lby two steps. Thereby the relay F is energized over the auxiliary switch MS l, and the relay opens its contacts 20 f and 24 f to disconnect the bridging relays A l and B l of the repeaterUe l`. The second train of impulses positions the wiper 3l oit' the auxiliary switch MS ot the repeater U e on the contact 37, thereby complet- ;ing the following `circuit `tor relay yU:

ground,fw1per 31, contact 37, winding of U,

' local exchange.

battery, ground. Relay 'U operates and by closing its contact 38 u, establishes they tollowing circuit for 'the relay U lshown in the drawing at the secondary presel-ector I. VNV.: ground, winding of U l, wiper 3.91ct the second preselector ILVV, contact 40. linejlead CZ, front Contact 38 u, battery, ground. `The relay U l energizes in this circuit and closes its contact 4l u1, thereby interrupting the test `conductor 0j The closing of the Contact 41 'ul also in known manner connects the rotary magnet of ILVVV to the interrupter again. The second preselector rotates its wipers and hunts tor an idle line in the second contact row 64 (seeFigure l), containingl the lines leadingto the Vhen` an idle line is found, the wipers stand4 on the contacts 42, 48, 44. The following circuit is formedover the wiper 39: ground, winding of U 1, wiper 39,

contact 44, line lead cl, winding of C G, earth. The succeeding trains of impulses operate the bridging relays A 3 and B 3 of the final selector LV l in known manner, and cause the switch to be positioned onto the line kot the wanted subscriber Te 3211.

The manner of setting up a call from the subscriber Te 3300 of the intermediate exchange ZA to the subscriber Te 8311 `of the same' exchange, will now be described. When the iirst and second preselectors have been positioned, the following circuit is es-` tablished for the winding I ot the relay C 5':

ground, battery, windings ofl test relay Tu and test wiper ot the first preselector, contact 5l u 4, test wiper of the `secondpreselector, contact 19 S, winding `of relayV C5,

ott normal contact K l, to ground. (l 5`at its contact 45 c 5 closes a locking circuit for itself yindependent of otl' normal Contact K l. At its cont-act 46 c 5, the relay C 5 closes a circuit t'or the relayVB. V 3 closes its contact 47 u 3, thereby disconnecting the relay S and short circuit/ing` relay P in order to prevent the sub-excl-iange UA taking into use vthe iirst group selector LGVV at the main exchange. The bridging relays A. 4 and B 4 are operated over the subscribers loop'. The

lfirst train of impulses positions the auxiliaryk switch MS 2 and the first group selector LGW at lthe main exchange HA in 'accordance with the selected number 3:.(the Afirst digit of the selected line). The second train ot impulses (second digit 3 ot' the selected line) positions the wiper 48 ot the auxiliary yswitch MS 2 onto the contact 49. Thereby the following circuit is established for the relay U8: ground, wiper 48, contact 4,9, winding oit U 3, battery, ground. The relay U 8 closes its contact 50 u 8 located in the circuit ot thetourth wiperot the second preselector and establishes a circuit tor the relay U 4. The latter closes its contact-5l u 4,

-tor ILVVV (see Figure l) and at the same tin'ie-starti'ng the rotaryiinagnet of ILV-'VV- in a known manner by means of -other contacts. The switch rotates its wipers .andhuntsfor lan idle line in the second contact. row, which contains the lines going to the local exchange. After such a line has been found, the wipers of-II.V\V stand on the contacts 52, 53, 54. Thus a circuitis established for the relay C 4 over-'the wiper 55 of the second preselectorILVlV. The connecting devices `at the main exchange HA were again rendered vavailable utter the contact v51 u 4 `was closed. yThe remainder of the trains of impulses are now transmitted corresponding to the number Il of the wanted subscriber. Thereby thebridging relays A 2and B 2 are operated as usual, and thetinel selector LIV is positioned on the line ot thewanted subscriber Te 3811. At the termination of the call, the connection is released in the well known usual manner.

That is claimed is: y

1. In .a telephone system, an automatic main exchange,-accessible. over a common trunk line to aplurality of tributary automatic sub-exchanges located serially with respect to each other, calling and called substations in said exchanges, switching means in said tributary exchanges for automatically seizing said common trunkline upon va substation initiating a call, and substation controlled means for releasing said switching means from connection with said common trunk line and rendering said Vtrunk line available, if said connection initiated :by said calling station is to be extended to one ot said tributary exchanges.

2. Ina telephone system, an automatic main exchange, accessible over a common trunk line to a plurality of tributary automatic sub-exchanges located serially with respect to each other, other trunk lines connecting said tributary exchanges, calling and called substations in said exchanges, switching means in said tributary exchanges for automatically engaging said common trunk line upon a substation initiating` a call, and substation controlled means for releasing said switching means from engagement with said common trunk lineiand for re-opera'ting said switching means into engagement with one ot said other trunk lines it said connection initiated by said calling station is to be extended to one of said tributary exchanges.

3. In a telephone system, an automatic main exchange, accessible over a common trunk line to a plurality of tributary automatic sub-exchanges located serially with respect to each other, calling and called substations in said tributary exchanges, switching means in said tributary exchanges for automatically extending the talking conductors of a calling substation to said common trunk line, other trunk lines, means for interrupting vthe extended connection, and means for .automatically operating said switching means to connect said calling substation to one of said other trunk lines if said connection initiated at said calling station is to be extended to one ot said tributary exchanges.

4. In a telephone system, an automatic main exchange, accessible over a common trunk line to a plurality of serially located tributary automatic sub-exchanges, calling and called substations provided with sending devices, switching means in said exchanges susceptible to current impulses generated at said sending devices under subscriber control, for extending a connection from a calling toa called station, and automatic nonnumerical switches controlled by said switching means for extending the talking conductors ofa calling substation initially to said common trunk line and for then re-operating and extending said calling station to -anothertrunk line if the impulses transmitted from said calling station signify that the connection is to be extended to one of the tributary exchanges.

5. In an automatic telephone system, a main exchange accessible over a common trunk line to a plurality of tributary exchanges, otherv trunk lines connecting saidv tributary exchanges, said trunk lines terminating in an automatic non-numerical switch, calling and called substations provided with impulse sending devices, means effective upon the initiation of a call at a calling station for operating said non-numerical switch to engage said common trunk line, and means responsive to the impulses transmitted at said calling station for reoperating said non-numerical switch to env gage one of the other trunk lines if the connection is to be extended to one of said tributary exchanges.

6. In an automatic telephone system, a main `exchange accessible over a common trunk line to a plurality of tributary exchanges, other trunk lines connecting said tributary exchanges, said trunk lines terminating in an automatic non-numerical switch associated with a repeater, a numerical switching device individual to said repeater and controlling said non-inunerical switch, calling and called substations provided with impulse sending devices, means ettective upon the initiation ol a call at a calling station for seizing said repeater and for automatically actuating said non-numerical switch to'engagc said common trunk line, means responsive to the impulses transmitted at said cal'ling station for operating said numerical switching device, and means actuated by said numerical switching device for reoperating said non-numerical switch to cngage one of the other trunk lines if the impulses transmitted from said calling station Vil() to one of the tributary exchanges.`

calling and'called lines provided with im- 7,. In an automatic telephone system, a plurality ofexchanges, trunk lines connecting said exchanges, said trunk lines arranged switch, calling and called lines provided with impulse sending devices, means effective upon the initiation of a call at a calling sta` ytion for actuating said non-numerical switch to engage the first idle trunk line available in a certain group, and switching means responsive to thek impulses transmitted at the calling station for 11e-actuating said non-nuvinercial switchto select a trunkline within another group.

8., In an automatic telephone system, a plua rality of exchanges, trunk linesy connecting said exchanges, said trunk lines arranged in groups accessible to a non-numerical switch,

pulse sending devices, means efl'ective` upon the initiation of a call ata calling station for actuating said non-numerical switch to engagethe iirst idle trunk line available `in ,a

certain group, and switching means responsive to the impulsestransmitted at the calling lstation for re-actuating said non-numerical switch to select a trunk line within vanother group, said re-routing of a partly establishedconnection being determined by the first train of impulses transmitted at the calling station.

9, In an automatic telephone system, a plurality of exchanges, trunk lines connecting said exchanges, said trunk lines arranged in groups accessible to a non-numerical switch,

calling and called lines provided with impulse` sending devices, means effective upon the initiation of a call at a calling station for actuating said non-numerical switch to engage the lirst idle trunk line available in a certain group, switching means responsive to the impulses transmitted' at the calling station for resactuating said non-numerical switch to select a trunk line. within another group, said re-routing of a partly established connection being determined by `the first train of impulses transmitted at theca'lling station, and effective only if the yimpulses signify lthat the connection is to be extended to a Vwanted substation within said other group. f y 10. In an automatic `telephone system, calling and called substations provided with impulse sending devices, trunk lines leading in 'a `lirst traffic direction and trunk lines lead-` ing in aysecond trafic direction, said trunk lines arranged in groups accessible to an automatic non-numerical switch, means effective upon the initiation of a call at a calling subs-station -for automatically actuating said non-numerical switch to select an idle trunk line within said lirst group, and means individual to said selected trunk line and reiny groups accessible to a non-numericah puise sending devices, trunk lines leading..`

sponsive to directive impulses generated at y tlie calling station for re-operatingsaid nonnuiiiericai sivitchto se'lect atrunkline within said second group..`

il. 'in an automatictelephOnesyStem, call-' ing and called substations provided with im-r in a tirst ti'aliic direction aiidtiuiili lines leading in a, second tral'tic direction, said trunk lines arranged in groups accessible to an automaticy nonnumerical switch, means ell'ective upon tlie initiation koll a call at a and responsive kto directive impulses gener-` ated at the calling station for re-operating `said*non-numerical switch to select a trunlr line within said second group, said rerouting elia, partly established connection beingde termined by the second train oit impulses transmitted attlie calling stati/n, i

l2.' ln an automatic telephone system, call ing and called substations provided with iinpulse sending devices, trunlrlines leading in a lirst tramo direction and trunk lines leading in a second traliic direction, said trunk lines arranged in vgroups accessible to an automatic non-numerical switch, means etlective uponthe initiation of a call at a Vcalling substation l'or automatically actuating said nonnuinerical switch to select an idle trunk line within saidtirst group, means individual 'l to said selected trunk line and responsive to directive impulses generated at `the calling station for reloperating saidnon-numei'ical switch to selecta trunk line within said sec-v ond group, said re-routingot a partly estabf lished connection being determined by the second train ot' impulses transmitted at the calling station, and ei'ective only it the impulses signity that the connectionis to be extended in said secondtraliic direction. -1

13. In an automatic telephone system, callTH ing and kcalled substations provided with impulse sending devices, two groups of trunk lines accessible to a lirst non-numerical switch and leading in a lirst and second traflic direction, the trunk lines within the rst group terminating in a second non-numerical switch having access rto two additional groups of trunk lines leading in athird and fourth traliic direction, means etlectve upon the initiation of a call at a calling station for operating said first and said second switch into engagement with idle trunk lines in said first and said third group, respec tively, and numerical switching means indi? vidual to the selected trunk line of the first its group and responsiveto directive trains of Y ing and; rcalled?v substations'K provided Vveli-tin impulsejsendingdevices, twogroupsrof trunkIv lines` accessible to 'a' Vfirst "non-numerical? switch and leading in a rstandsecon'd"traf# yfic"direction;tlietrunkA lines `VWithinthe first g'llpitern'rinating-in' asecond nonsnumerical switch-"having access` to' two#additionalgroups `oftrunlrllinesleading'ina third andY Y fourth 'traffic direction; means efi'ectiveupon'jk the initiation of-aicall at a calling'station for opera'ting' said? first rand Vsaid second switch' into `'engagement 'idle trunk'lines in said firstwv and; said 'third' l group, 'respe'ctivelylv and selected. 'trunklineI ofthe nfirst group and re# operatingjsaidst switch to 'engagera ltrunk' deter'mi'n'edljylthe-second train of- 'impulses y tiansinittedatthe-icalling station?A f Y 15. In anautoinatic telephone system; call--v A ingindcfcalled"substationsprovi'ded with' im- 25' l i lines' accessiblet nonnumericalfswitch,

andleadingin* a first andsecond' traffic Vdi# rection, the trunlcliieswithin' thefirst groupl terminating'finf ai second? noir-#1mine'ricaly switch?y *having* access 'totwo '5 additional "grimpe oftrunlt lines leadinglinfathird' and Y "fourtht traffici?directiong-'means effective upon t foroperatingfsaid 'first and said second:- '35 switch into'A engageinent"l1 with? idle trunk lincsin said'first'andsaid'fthirdgroup; re-

spec'tively,'fand iIinn'ericaly switching means individual rto2 the-,lselecteditrunlr "line of' the firstgroup and 4'resp'onsive to Vdirective' vtrains ofi'l impulfsesftransmittedi 'atthe calling' station y for re-operat1ngsaidfirstiswitch to engage at trunk linelwitlrinvsaid second group,`and= effective only ifsaid second train 'off' impulses signifiesthat the connection -isto be extended in' said secondl'tra-fc' direction; y y -1'6 In air automatic" telephone' system, call-` ing and icalfl'e'd-"suhstations' provided lwith irn-y v pulseA sending.' devices, itwo groups of trunk individual f toi-thefselecfed'- trunkline ofy the firstgroup' and responsive todirective'trains oiv impulses transmitted Aat the calling station forI 12e-operating s'aid-second-switchl to engagea trunl'rlineWithinsaid fourth group.

wry-ese? 17;" In an automatic telephone system, callin@r and calledajsuljstations providedy with in'ipulsef-sending devices, two` groups of trunlrlines accessible to' a first non-numeri-i cal 'switch and vleading in afirst- 'and secondf traflic direction, the trunk lines Within' the first, l'group terminating in` a'second non-,nw merica'l* switch--having yaccess' tok two addii tionalf'groups of' trunklines leading in al thi-rdand vfourth trafficdirection;` mea-ns ef#-v fecti'v'e' upon the initiationv of a call vat" ay calling-'station -i'or operatingy said first" andv said second`r switch into engagement with? idle'irunk lines iii-said first and'said'third group, respectiif'ely, and numerical krswitching means individual ,to the selected trunk; lin'eio'f the-firstgroup andv responsive to d1- rective -t rains of impulsestransmitted f atthe calling, ystation `for v're-operating, sald second switch ifo engage a- 'trunk line Within said established* connection being determinedx '-by, thel firstf-trzrinL ofi impulses'A transmitted at' thecalliiigfstation.V

118i.v I'xr'anautoniaticfy telephone system,- ca'lls' a in'gfandicalled substations provided with im'- pulse -sendingde'v-ices, two groups of trunk' linesy 'accessible1 -toy ai first: non-numerical sivitch andfleading in a first-and-second'trafl fic direction, the *tru-nk# li-nes- Within the first# group terminatingin a second nonsnumeri-y calf switch l hafving access= to -two additional groups of" trunk lines leading ini a third' andjfourth trafii'c`r direction, meansieflfectiye upon vthe initiation -of'f a call 'at a calling sta-` tion;f'orfoperatiugl said firsty andi said sec# ond switch intoengagementfwith idle trunk:

spectively, Y and numerical switching means individualito the selected trunk1 line of' the firstgroup and'responsive to directive trains 0f impulses transmitted'fatv theI calling sta-l tionl -for-ue-operatingf said 1 second switchI to' engage a-trunkI linefjwithin said fourth group-,said red'outing'off a-A partly estabfA lished connection beingdetermined by: the first4 train of' impulses transmitted atl the callinglistation, fand=vefi`ective only iff-'said first train: of impulses signifies that the tconnectionis t0 be extended in said fourth traf'-k fic direction. e,

l* 19. In an automaticftelcphone system, call ing and called stations provided with im'- pulse-,send-ing devices, ay first' and a second exchange, a trunkline 4accessible tol a'first vautomatic non-numerical'switch insaid` first exchange' and terminatinfgin a second alito-l matic noni-numerical switch insaid' second exchangeand havingaccessL to groups of trunk linesfleading in other' trafiic direc-r tions, said `'trunk lineAL being provided at both ends with afnumerical fswitchingdevice ind-i-vidualy thereto, means effective uponthe initiationy ofi as' calli atv af substation fon opf erating said firstj'switch'fto select saidv trunk fourtlr-groupy'said re-routing of' a partly* ist line, means etlective upon seizure of said trunk line for operating said second switch to .further extend the call, and means controlled by said numerical switching devices responding to the digits generated at said calling station, for re-operating said `first or said second non-numerical switch to select a trunk line in other groups, depending upon the tratlic direction signilied by the digits.

20. In an automatic telephone system, calling and called stations provided with impulse sending devices, a first and a second exchange, a trunk line accessible to a tirst automatic non-numerical switch in said first exchange and terminating in a second automatic non-numerical switch in said second exchange and having access to groups 0f trunk lines leading in other trallic directions, said trunk line being provided at both ends with a numerical switching device individual thereto, means effective upon the initiation of a call at a substation for operating said first switch to select said trunk line, means effect-ive upon the seizure of said trunk line for operating said second switch to further extend the call, and nieanscontrolled by said numerical switching devices responding` to the digits generated at said calling station,

:tor reoperating said first or said second non? numerical switch to select a trunk line in other groups, depending upon the tratiic direction signified by the digits, the re-operation o' said first switch being determined by the second digit and the re-operation of said second switch being determined by the first digit.

In witness whereof, I hereunto subscribe my name this 26th day of October, A. D.

MAXIMILIAN MATHIAS. 

